Method of forming brake drums



Jan. 9, 1934. J. Ma LENNAN METHOD OF FORMING BRAKE DRUMS Filed July 18, 1932 2 Sheets-Sheet 1 {02177 fiaczezwarz Jan. 9, 1934. J. Ma LENNAN METHOD OF FORMING BRAKE DRUMS Filed July 18, 1932 2 Sheets-Sheet 2 Patented Jan. 9, 1934 UNITED STATES PATENT OFFICE John MacLennan,

Kelsey-Hayes Detroit, Mich, assignor to Wheel Corporation, Detroit, a corporation of New York Application July 18, 1932. Serial No. 623,243 6 Claims. (01. 23-1522)- The invention relates to brake drums and refers more particularly tothe method of forming the same. One of the objects of the invention is to provide an improved method of forming a br e drum and more particularly a composite brake drum. Another object is to so form the: body of the brake drum that it will be round and true and will have accurate predetermined. dimensions. A further object is to provide an m economical method of forming the brake drum.

These and other objects of the invention will become apparent from the following description, taken in connection with the accompanying drawings, in which Figures 1 and 2 are, respectively, a plan view and a side elevation of a blank used in the forming of the brake drum, according to the method embodying my invention;

Figures 3, 4, 5, 6 and 7 are cross sections through the brake drum body showing different stages in its development;

Figure 8 is a cross section through the completed brake drum;

Figure 9 is a plan view of the completed brake drum.

The brake drum formed by the method embodying my invention, as illustrated, is particularly adapted for use with motor vehicle wheels and, as shown in Figure 8, comprises the body l and the lining 2. The body is formed of sheet metal and more particularly sheet steel and has the back or web 3 which is provided with the central or axial opening 4 and the peripheral annular flange 5 which is provided with the annular outiwardly extending rib 6 intermediate its edges,

the annular outwardly extending rib 7 connecting into the back or web, the annular outwardly extending rib 8 near its free edge and the inwardly extending and inclined flange 9 at its free edge.

The lining 2 is a casting and preferably a centrifugal casting which is fused throughout its extent to the annular flange and the adjacent portion of the back or web.

The body 1 is formed from the flat circular sheet metal or sheet steel blank 10, shown in Figures 1 and 2. This blank is cupped as shown in Figure 3, to provide a flat back or web and a peripheral annular flange and after the cupping operation the blank is then reduced, as shown in Figure 4, to decrease its diameter and increase the width of its peripheral annular flange. The blanks, as shown in Figures 1, 2, 3 and 4, may be formed on an ordinary press.

The next step in forming the brake drum body consists in redistributing the metal of the flange of the reduced cupped blank. This is accomplished. in the present instance by rolling the flange and forming therein and intermediate its edges the outwardly extending annular bead 11 and decreasing the width of the flange, as shown in Figure 5. The body blank is then rolled. to the shape shown in Figure 6 to have the outwardly extending annular bead 12 intermediate its edges, the outwardly extending annular bead 13 connecting into its back. or web, the outwardly extending annular beadv 14 near its free edge, and the inwardly extending inclined flange 15 at itsfree edge, the bead 12 being in the zone of the bead 11 of the preceding blank and formed therefrom. After the second rolling operation the body blank is then subjected to a sizing operation by being placed in a shrinking machine which shrinks the annular flange and makes it round and brings it to accurate predetermined dimensions and, furthermore, stabilizes or sets the metal, so that it will not spring out of shape. The body blank is then pierced to provide the axial or central hole 4 and placed in a centrifugal casting machine and while it is heated to the proper temperature and While it is being rotated at the proper R. P. M. the molten metal, which is preferably ferrous, is poured into its flange, after which rotation continues until this molten metal has cooled and solidified, after which the brake drum, as thus far completed, may be removed. It will be seen that the ribs 6, '7 and 8 of the brake drum, as thus far completed, correspond to the annular beads 12, 13 and 14, respectively, and

that the inwardly extending flange 9 corresponds to the inwardly extending flange 15.

After the centrifugal casting operation, the brake drum may then be operated upon to provide the necessary holes 16, 17 and 18 and to finish the inner or brake engaging face of the linmg.

What I claim as my invention is:

1. The method of forming a brake drum, which comprises cupping a sheet metal blank, rolling the flange of the cupped blank to form an outwardly extending annular bead therein intermediate its edges and to decrease the width of the flange, again rolling the flange to form a plurality of outwardly extending beads therein, shrinking the roller blank to make the flange round and of predetermined dimensions and to stabilize the metal, and then casting a lining within the flange.

2. The method of forming a brake drum, which comprises cupping a sheet metal blank, redistributing the metal of the flange of the cupped blank by increasing the diameter of a portion thereof and decreasing the width thereof, operating upon the flange to form an annular outwardly extending bead from said increased portion and to form an inwardly extending flange at the free edge of the flange, shrinking the body and flanged flange to make the same of predetermined dimensions, and casting a lining within said flange.

3. The method of forming a brake drum, which comprises cupping a sheet metal blank, redistributing the metal of the flange of the cupped blank by increasing the diameter of a portion thereof and decreasing the width thereof, operating upon the flange to form an annular outwardly extending bead from said increased portion and to also form another annular outwardly extending bead, shrinking the beaded flange to bring the same to predetermined dimensions and to stabilize the metal, and then casting a lining within the flange. 4. The method of forming a brake drum, which comprises cupping a sheet metal blank, reducing the cupped blank by reducing its diameter and increasing the width of its flange, redistributing the metal of the flange by increasing the diameter of a portion thereof and decreasing the width thereof, operating upon the flange to form an annular outwardly extending bead from said increased portion and to form an inwardly extending flange at the free edge of the flange, shrinking the headed and flanged flange to make the same of final predetermined dimensions and to stabilize themetal, and casting a lining with: in the flange.

5. The method of forming a brake drum, which comprises cupping a sheet metal blank, reducing the cupped blank by reducing its diameter and increasing the: width of its flange, rolling the flange to form an outwardly extending annular bead therein intermediate its edges and to decrease the width of the flange, then rolling the flange to form a plurality of outwardly extending annular beads therein with one of the beads formed from the first mentioned bead, shrinking the rolled blank to make theflange round and of final predetermined dimensions and to stabilize the metal, and then casting a lining within the flange with the latter heated to secure effective fusing between the former and the latter.

6. The method of forming a brake drum, which comprises cupping a sheet metal blank, redistributing the metal of the flange of the cupped blank by rolling the same to increase the diameter of a portion thereof and decreasing the width thereof, rolling the flange to form an annular outwardly extending bead in the zoneof said increased portion and to form an inwardly extending flange at the freeedge of the flange, sizing the flange and setting the metal thereof, and then casting a lining within the flange.

JOHN MACLENNAN. 

